Session Index

Quantum photonics has advanced rapidly and become a promising technology for realizing various state-of-the-art quantum devices and systems advantageous for, e.g., communications, information processing, computing, and sensing applications. Various kinds of optical elements have been developed as building blocks using photonic integrated circuits (PIC) technology for different applications. For example, PIC has been widely used in the implementation of chip-based photonic quantum circuits where different building blocks like qubit sources, linear optical circuits, modulators, and even single-photon detectors are intended to be integrated in a common substrate. Such a powerful integrated scheme has been applied to build photonic circuits for the creation, manipulation, and test of quantum entanglement states from the generated qubits as well as in implementing a reprogrammable logic gate circuitry for quantum computing. Lithium niobate (LN), renowned as “the silicon of photonics”, has been long a popular material widely used in integrated-optical and nonlinear-optical applications. A great variety of passive and active photonic elements have been realized in the LN platform. Recently, a novel material based on high-quality single crystalline films of LN has been developed and soon draws enormous attention for its greatly promising ability to realize nanoscale integrated photonic circuits/devices in this iconic optical platform.

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In this work, we first break the parity symmetry to induce topological phase transition and further investigate topological edge state lasing for it can be immune to defect and possess robustness. We break the parity symmetry by expanding and shrinking the airholes on honeycomb lattices. By combining them, topological edge state and special lasing state are observed with and without grating coupler, respectively. Furthermore, topological edge state demonstrates chiral characteristics, with two states propagating in opposite directions. It is the topological edge state with these traits that advances the research in integrated photonic devices.

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Period-one (P1) nonlinear dynamics of semiconductor lasers can be induced when subject to external optical injection. By analyzing how P1 dynamical states with different characteristics respond to perturbation superimposed onto the external optical injection, the stability and instability of the lasers at P1 dynamics are experimentally investigated.

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Tracking biomolecules is important in the biomedical field for unraveling the intricacies of various cellular processes. Conventional fluorescence-based imaging methods rely on a potentially harmful click-reaction to attach fluorophores to target biomolecules. These relatively bulky labels not only disrupt native bio-systems but also introduce issues such as photobleaching and phototoxicity, restricting their utility in live and long-term observations. Stimulated Raman scattering (SRS) has emerged as a promising solution for directly capturing the chemical information of biomolecules. Here, we visualize de novo synthesis of RNA at both cellular and tissue levels, exemplified with alkyne-tagged U2os cells and Drosophila larvae brain.

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MAPbBr3 perovskite nanofibers were synthesized using the uniaxial electrospinning method. A blend of PAN and PMMA polymers was used as the matrix to achieve a balance between stability and optical performance. The resulting nanofibers exhibited a distinct bamboo-like structure. These perovskite nanofibers, encapsulated by polymers, demonstrated robust and stable fluorescence even after immersion in water for extended periods. Notably, these MAPbBr3 nanofibers formed at the junctions of the bamboo-like fibers, exhibiting lasing effects under pulsed laser excitation. The observed waveguide lasing behavior was attributed to the Fabry-Pérot (FP) cavity when the excitation power exceeded the threshold.

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In this manuscript, we overcome the lattice mismatch between the AlGaAs distributed Bragg reflectors and Germanium substrate and successfully fabricate Germanium-based 940-nm vertical-cavity surface-emitting lasers (Ge-VCSELs) with an 8 μm oxide aperture. Also, we provide a comprehensive analysis of the static performance of the device, operated at a bias current of 7.5 mA, exhibits an optical output power of 1.4 mW, a slope efficiency of 0.312 W/A, a wall-plug efficiency of 0.1093, and a roll-over current is 22 mA.

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Despite the challenges associated with implementing a distributed-feedback Bragg reflector for VCSEL in the short-wavelength infrared (SWIR) range, there has been a growing demand for surface-emitting lasers operating within this spectral range. We successfully demonstrate the operation of 1580 nm photonic-crystal surface-emitting lasers (PCSELs) with an impressive slope efficiency of 0.46W/A, and the divergence angle of the output beam is about 1 to 2 degree. Additionally, we conducted a comparative analysis of PCSELs with different photonic crystal patterns to explore their performance characteristics.

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An efficient dual-wavelength CW mid-infrared laser is demonstrated using an intracavity optical parametric oscillator (OPO). By using the dual-wavelength pump wave from a composite Nd:YVO4/Nd:GdVO4 gain medium, the quasi-phase-matched (QPM) OPO process is found to have shared resonance at signal wave share for reducing threshold power.

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We have demonstrated a compact and cost-effective ytterbium-doped all-fiber laser operating at 976 nm. By utilizing a commercially available ytterbium-doped fiber with a length of only 18 cm, we achieved a lasing power of 10.3 W, with a slope efficiency of 25.4%. To our knowledge, our work presents the shortest gain fiber ever documented in the literature capable of delivering tens-of-watt 976-nm lasing power. The design is compatible with conventional fiber components, simplifying the monolithic assembly process. Notably, the incorporation of such a short gain fiber obviated the need for additional measures to suppress the strong 1.03-μm emission.

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A hybrid system is proposed in this study, which combines optical injection and optoelectronic feedback to generate a square-wave signal while analyzing the relationship between the delay time of modulation and the frequency and waveform. In addition, the impact of frequency peak density on the flatness of the square waveform is investigated. This research provides a new option for existing square-wave signal generation techniques and has the opportunity to reduce the cost and complexity of future signal generation and electronic equipment.

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Focusing the laser pulse into a capillary filled with neon gas for interaction, and generating phase-matched HHG in the water window by balancing plasma dispersion with dipole phase. The result of using ANSYS to simulate the flow field in the capillary show that this design can achieve the gas density distribution required for the experiment.

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An LED-side-pumped Nd: YAG/Cr4+: YAG passively Q-switched (PQS) laser containing an extracavity optical parametric oscillator (EOPO) is demonstrated. The PQS pulse energy is optimized to 24 mJ at 1064 nm. By using the double-pass EOPO operation, the pump-to-signal conversion efficiency increases to 45.8%, the output energy of the signal pulse is up to 10.98 mJ with a pulse width of 23.5ns, and the peak power is 459kW. This study demonstrates the possibility of using LED-pumped eye-safe lasers to achieve low-cost, long-range flash LiDAR systems.

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A new mode-locked fiber laser configuration based on a silicon-photonics micro- ring cascaded with an electro-absorption-modulator is carefully examined. We experimentally demonstrate both active and passive mode-locking operation in the same configuration. The distinctive features of the laser are the highly stable pulse train and the wide coherent optical comb spectrum.

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We optimized the waveguide structure of two types of InGaN-based photonic crystal surface-emitting laser (PCSEL) via optical mode simulation. In order to minimize threshold materials gain (gth), we calculated the confinement factor and quality factor of PCSEL with varying waveguide layer thicknesses in the separate confinement heterostructure (SCH). Optimal mode intensity profile revealed the coupling between the fundamental mode of SCH and parasitic leaky modes in the cladding layer or substrate as the main root cause of a low quality factor. With an optimized thickness design, gth of PCSEL with air voids in the n-side could be below 2000 cm-1.

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In this paper, chaotic pulses are generated in semiconductor lasers subjected to both optoelectronic feedback and optical injection by numerical simulation. The detuning frequency between the two semiconductor lasers is the key factor to generate chaotic pulses. The chaotic pulses generated show the broad bandwidths of around 38 GHz and the magnitude drops are effectively reduced in frequency domain compared to the semiconductor laser only applying optoelectronic feedback loop.

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We investigated the random lasing characteristics of cesium lead bromide quantum dots (CsPbBr3 QDs) on patterned silk fibroin (SF) films. The patterned SF film was produced from nanocasting of rose-petal. By applying mechanical stress on the flexible PET substrate, the flexible RL was demonstrated with a 7.7 nm blue-shift relative to the flat CsPbBr3 QDs/SF film.

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The most common approach to investigate the pulse width of an ultrafast laser is through autocorrelation by either two-photon absorption (TPA) or second-harmonic generation (SHG). However, in comparison, SHG-based measurements are more inconvenient as they require a phase-matching condition and may necessitate a sensitive detector. Conversely, TPA-based measurements are simpler and more cost-effective, utilizing only a photodiode or light-emitting diode (LED). Our study employs an ultraviolet (UV) photodiode to generate the TPA signal and directly harvests the corresponding current through a source meter—eliminating the need for amplifiers, oscilloscopes, or data acquisition systems (DAS).

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At high power, stimulated Raman scattering competes with stimulated polariton scattering to saturate the THz-radiation output from a THz parametric source. We demonstrated the generation of ultra-high-power narrow-line THz radiation from KTP by suppressing the stimulated Raman scattering, achieving 17.2-μJ pulse energy over an ~80-ps pulse width at 5.7 THz.

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A narrow-linewidth DFBLD with the <±0.0001°C feedback control exhibits an ultra-long-term wavelength stability of <0.1pm for secure BPSK encryption and decryption. The delay-interferometric decoding the BPSK security code with a bit-amplitude fluctuation of <0.5% is demonstrated to enable an error-free BER of <8.6×10^-10.


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The development of compact, efficient and high quality postcompression schemes for laser pulses of relatively low μJ-level energies is of particular interest for MHz high-repetition rate fiber lasers. Here, we demonstrated the use of an all-solid-state medium within a Herriott-type multi-pass cell to postcompress 3 uJ femtosecond pulses from 172 fs to 47 fs with an efficiency of 72%.

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Spintronic terahertz (THz) emitters with ferromagnetic (FM) and non-ferromagnetic (NM) metallic heterostructure have several advantages over conventional THz emitters, such as photoconductive antennas (PCAs). The emission bandwidth is much broader than that of a typical PCA. The spintronic THz emitters are robust, and a broad range of optical pump wavelengths from UV to mid-IR region is usable. However, the efficiency of spintronic emitters is still low compared to PCAs. Therefore, improvement of the THz emission efficiency of spintronic emitters is required for practical applications. Fe(FM-layer)/Pt(NM-layer) heterostructure is one of the most efficient spintronic THz emitters among those reported so far. In this paper, the optimization of the Fe/Pt hetero-structures for efficient THz emission is reported considering the following points: the FM and NM layer thickness, the optical pump wavelength, the choice of the substrate, and the out-coupling efficiency to the free-space. To improve the out-coupling efficiency, we introduce antenna structures with various shapes. It has been demonstrated that a well-designed antenna structure can enhance the THz emission efficiency by 5-6 times. In addition, the authors will report a magnetic-field bias modulation, with which the signal detection efficiency can be almost doubled.

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THz photoconductive antennas (PCAs) have found widespread use in THz generation, detection, and various applications such as sensing, imaging, and communication. For achieving ultrafast operation, most commercially available THz PCAs rely on III-V epitaxial materials due to their high mobility and ultrafast response. However, launching the entire device fabrication process through IC foundries presents significant challenges, thereby limiting the capability of device mass production. In this study, we propose the use of GeSn alloys as the photoconductive material for THz generation. Furthermore, the use of GeSn alloys can offer additional advantages such as cost-effective, scalable, and improved performance.

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We present an optoelectronic transmitter at 300 GHz, composed of a uni-traveling-carrier photodiode module, a fundamental mixer, a filter, and a horn antenna. The designs of those waveguide-based components will be shown.

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The challenges of THz electronics in CMOS technologies for THz sensing and communication applications are addressed in this work, focusing on device-level design to system integration approaches. State-of-the-art THz circuits, components, design methodologies, and system demonstration were proposed, including a 40-nm-CMOS transistor layout design using an electromagnetic modeling approach, a 340-GHz higher-order-mode high-gain dielectric resonator antenna, a 340-GHz CMOS heterodyne receiver, a 340-GHz heterogeneously-integrated THz transmitter with 2×25 antennas, a THz heterogeneously-integrated platform, and a THz transmissive imaging system with a spatial resolution of 1.4 mm at 336 GHz.

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We demonstrate the emission and detection of orthogonally polarized terahertz pulses simultaneously in a fiber-coupled time-domain system. Here, a multi-pixel emitter multiplexes the s- and p- states with different modulation frequencies and the detected signal is demultiplexed with post-processing. A commercial photoconductive detector is used and the the photoconductive emitter is made using standard lithographic techniques. This work can significantly improve the speed of polarization-resolved THz spectroscopy and imaging, so we demonstrated its efficiency by imaging an anisotropic metamaterial and characterizing birefringent crystal.

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Shift and injection currents unveils the pivotal role of the topological band structures and is a prerequisite to development of advanced photovoltaics. This is especially interesting for chiral Weyl semimetals that were proposed to exhibit giant quantized circular photogalvanic effect (CPGE). Here we report a comprehensive THz emission spectroscopic analysis for quantifying nonlinear optical conductivity spectrum of undoped CoSi. Results confirm photoexcitation of giant circular injection currents but provide limited evidence of the quantized CPGE. Moreover, the linear shift current is found significantly weaker. This work consolidates the THz spectroscopy as a contact-free in situ ammeter for probing ultrafast photocurrents.

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We present a theory on refractive index tuning for symmetry-protected bound states in the continuum (SP-BICs) in high-contrast gratings (HCGs). Our study introduces a compact analytical formula for tuning sensitivity, verified through numerical analysis. Additionally, a novel type of SP-BIC in HCGs is discovered, characterized by an accidental nature with a spectral singularity. This behavior is explained by hybridization and strong coupling among the odd- and even-symmetric waveguide-array modes. Our research provides valuable insights into the physics of tuning SP-BICs in HCGs, offering simplified design and optimization for dynamic applications in light modulation, tunable filtering, and sensing.

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We applied metal-dielectric interactions to induce Localized Surface Plasmon Resonance (LSPR) in terahertz (THz) metamaterials. Two studies introduced a graphene-based filter with adjustable resonance peaks and a graphene-metamaterial ultrabroadband absorber. By tuning graphene's Fermi energy, we controlled conductivity and resonance, impacting future THz communications. Another study integrated perovskite ZnTiO3 into a reduced graphene oxide aerogel for a sensitive THz metamaterial gas sensor. A high-surface-area ZTrGOA variant facilitated precise NOx detection. This compact, energy-efficient innovation holds potential for optical gas sensors in biomedicine and wearables, and the absorber's potential in silicon photonics for high-sensitivity 6G and THz communication is explored.

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In this work, we successfully postcompressed a high power (80 W) and high pulse energy (800 μJ) Yb laser from 187 fs to 30 fs with high energy efficiency of 94.3% using cascaded focus and compression (CASCADE). By utilizing this high-power Yb laser for high HHG, we generate coherent EUV radiation with an average power that reached as high as 20 μW (~2×1012 photons/sec), spanning the range from 45 to 70 eV.

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Time-frequency entanglement has been highly regarded in quantum technology due to its high-dimensional entanglement and resistance to practical disturbances. In this work, we utilize a Franson interferometer to verify the time-frequency entanglement of photon pairs generated from spontaneous parametric down-conversion. We observed a high visibility of 94% in the nonlocal two-photon interference. We further demonstrate the advantages of time-frequency entanglement by distributing the two photons through a 2.64 km fiber network at the NCU campus, and achieve an interference visibility of 88.9%, which surpasses the classical limit of 70.7% by a significant margin.

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We present the study of a THz free-electron laser consisting of 5 mm helically corrugated waveguide driven by a 10-mA annular electron beam at 30 keV. The structure is made of an M1.6 Metric thread in copper. The device is capable of generating laser-like radiation at the frequency of ~0.261 THz via backward-wave oscillation. Electron bunching is observed in our simulation study. We show that the coherent THz radiation and electron energy modulation have a helical profile due to the electron synchronism with a coupled higher-order TM mode satisfying the boundary condition of the helical corrugation inside the waveguide.

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We reported the use of monolithic quasi-phase-matched nonlinear photonic crystal(QPM-NPC) to enable simultaneous dual-optical parametric oscillations(OPOs) followed by serial up-conversion processes to generate tri-wavelength yellow-orange lasers. We further resolve the spatial distribution of the OPO wavelengths and the up-conversion components inside cavity. Despite the non-resonant dual-signals were spatially separated due to path-enabled QPM conditions, the resonant counterpart of the dual-idlers, however, maintained spatially overlapped and so did on the generated yellow-orange waves. These results suggest that the parallel QPM-NPC design can generate multi-oscillations of OPOs simultaneously, and it can also assist in the generation of spatially overlapped multi-wavelength visible lasers.

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We perform comparative modeling and simulation of a passive fs and a hybrid ps figure-9 mode-locked Er-doped fiber lasers by using the nonlinear traveling pulse propagation approach. The split-step FFT method is used to solve the generalized Nonlinear-Schrödinger-Equation for roundtrip propagation, allowing us to observe the lasing dynamics accurately.

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Proton-boron fusion is an interesting nuclear reaction because the reactants are non-radioactive and abundant on earth, and the reaction produces alpha particles without emitting neutrons. However, the activation energy of proton-boron fusion is 0.6 MeV, an order of magnitude larger than deuterium-tritium fusion. This large activation energymakes proton-boron fusion impractical in a thermal environment confined by magnetic field. Although it is not difficult to accelerate protons to 0.6 MeV by conventional accelerator or laser accelerator, because of the small ratio of fusion reaction cross section to proton-electron inelastic scattering cross section, most accelerated protons lose their kinetic energy to electrons instead of activating fusion reaction. In this talk, how high-field laser could hold the promise of mitigating these problems is discussed. The extremely large ponderomotive force and optical pressure of high-field laser not only can be utilized to accelerate protons, but also to expel electrons away from the path of laser beam and protons synchronously. Laser induced strong magnetic field may also be critical to confining the protons along the laser path against Rutherford scattering. Implementation of these ideas will meet great technical challenges which may be overcome by future development of high-field laser technology.

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In recent developments, cavity-enhanced optical chirality, represented by circular dichroism (CD), has been successfully demonstrated through the incorporation of special organic thin films within an optical cavity. This chiral amplification in CD-active cavities presents a promising pathway for constructing a chiral laser. In this paper, we explore the potential of constructing a chiral laser utilizing the dye POPOP as the laser gain medium, along with an optical cavity consisting of an output coupler and a high reflective (HR) coverslip mirror deposited with PTPO.

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Geometric modes with orthogonally polarized states are generated and explored in an off-axis pumped c-cut Nd:YVO4 laser with a symmetric concave-convex resonator. Due to the inherent birefringence of gain crystal, it is interesting to discover that the polarized state of the geometric modes under the same transverse-longitudinal coupling condition can be switched from s- to p-polarization when tuning from a shorter to a longer cavity.

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We demonstrated, to the best of our knowledge, the first electro-optically Q-switched LED-pumped Nd:YAG laser with the highest peak power on record. The measured output laser-pulse energy is 64.2 mJ within a 28-ns pulse width, corresponding to a peak power of 2.3 MW.

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We investigated the characteristics of VCSELs with varying structures, including different numbers of junctions and oxide apertures. We verified the performance of VCSELs under different short pulse. Throughout the study, we demonstrated the advantages of multi-junction VCSELs featuring a greater number of apertures are higher SE and lower threshold, attributed to their superior carrier confinement capabilities. Over 50W output can be achieved at 20A short pulse driving condition.

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This study introduces a novel digital laser setup with two adjustable phase boundaries to create orbital angular momentum (OAM) laser beams. Experiments confirm the effective generation of vortex beams, offering control over both OAM and intensity profiles. This innovative digital laser configuration represents a promising solution for customizable OAM beam generation, with wide-ranging applications.

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Intense 4.3-fs pulses at 1030 nm were focused into an Ar-filled gas cell, producing a 2-fs (sub-one-cycle) pulse, alongside isolated pulses lasting ~200 as, characterized by attosecond streaking. This study paves the way towards sub-one-cycle post-compression, advancing attosecond science.

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The impact of photons or energetic particles, such as electrons, introduces non-
equilibrium conditions in which many-body interactions can affect and determine the subse-
quent energy exchange pathways. These processes play an important role in surface-science
fragmentation and biological systems. In this study, we use real-time time-dependent density
functional theory (RT-TDDFT) to examine the autoionization process in water dimer, in which
initial inner shell ionization of a water monomer initializes an Intermolecular Coulomb Decay
(ICD) process that can further ionize the other water molecule leading to fragmentation of the
molecular species

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In this paper, regular pulses generated by the semiconductor lasers under optoelectronic feedback with ultrashort delay are analyzed and investigated. The study reveals a positive correlation between optoelectronic feedback strength and peak power. The higher the optoelectronic feedback strength, the higher the pick power and repetition frequency are observed. Detailed characteristics of the generated regular pulses are investigated, and the relations of each controllable parameter are also studied and compared.

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Dissipative soliton resonance in a unique mode-locking regime, which allows generating pulses with μJ level energies directly from the laser resonator. We present the first demonstration of using cross-phase modulation to synchronize the repetition rate of mode-locked fiber lasers working in the dissipative soliton resonance regime. High-energy synchronized pulses from lasers working at 1.06 μm and 1.55 μm are used to generate mode-locked pulses in the mid-infrared wavelength region via the difference frequency generation nonlinear effect. Parameters of the generated mid-IR radiation and the stability of the locking technique will be experimentally verified and discussed.

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This paper aims to investigate the influence of different C-ring sizes for N-metal electrodes on the
electrical properties and high-frequency characteristics of vertical-cavity surface-emitting lasers. Various C-ring
sizes were designed and measured under aperture sizes of 6 μm. The measurements include photoelectric
characteristic measurements, high-frequency response, and eye diagram analysis. The increase in the C-ring size
could lead to higher optical output power. However, for high-frequency communication, the parasitic
capacitance would be generated due to the increase in the N-metal area. Thus, the noise oscillation could lead to
a decrease in the high-frequency bandwidth.

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The laser-driven betatron source has matured to be one of the X-ray sources suitable for application in many research areas, its relatively compact footprint and permitting variable experimental geometries make it a possible alternative to large synchrotron radiation facilities. Our experiment used NCU 100TW laser system to generate ionization injection and utilize varying tilt angles of a sharp density transition to enhance X-ray production. The current results show that rotating tilt angles enhance the X-ray output signal by two times.

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This work presents the tunable generation of vortex, vector, and flat-top beams in a few-mode fiber with a mechanical long-period fiber grating. By the variation of applied force on the fiber grating, the core mode to higher-order mode excitation can be adjusted. The manipulation of the beam transformation is achieved through the polarization control of the fiber eigenmodes and mode coupling efficiency. By precisely tuning the intensity ratio between fundamental and doughnut modes, we arrive at the generation of propagation-invariant vector flat-top beams for more than 5 m.

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We present a surface modification of silicon nitride waveguide resonators using femtosecond laser annealing at 1035 nm. The surface morphologies were analyzed pre- and post-annealing using scanning phase-shifting interferometry and atomic force microscopy (AFM). Notably, at laser powers like 0.65W, surface roughness was enhanced to a mere 0.1nm. When applied to waveguide resonators, this annealing increased the quality (Q) factor by up to 1.33 times. Our study highlights the potential for efficient, cost-effective fabrication of low-loss integrated photonics through localized pulsed laser annealing.

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In this work, we constructed a range finder system using a homemade single longitudinal mode tunable laser and fiber coupled mach-zehnder interferometer. By measure the optical beat frequency between reference and return signals, the optical path difference can be calculated.

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Chirped mirrors present a valuable avenue for managing broadband dispersion in ultrafast optics, yet they are constrained by the extent of dispersion compensation. We've introduced a groundbreaking multiband design that redistributes group delay across various frequency bands, substantially boosting control and flexibility. Remarkably, the group delay dispersion of our mirror pair can be three to four times greater than that of existing ultrabroadband designs, with band separations exceeding an octave. Implemented in a multiphoton microscopy system, a chirped mirror pair successfully compressed pulses to their transform limits, 30fs and 23fs at 950nm and 1236nm wavelengths, respectively.

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We report the demonstration of an electro-optically (EO) switchable source based on a domain-engineered LiNbO3 operating in a closely lying, cross-polarized dual-line Nd:YLF laser. Simultaneous EO spectral switching and Q-switching at dual 1047- and 1053-nm cross-polarized lines, single 1047-nm line, single 1053-nm line, and their second-harmonic and sum-frequency generations have been realized with this novel laser system simply by voltage control.

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Modeling photoluminescence properties of a strong coupling unit consisting of molecules and a plasmonic nanocavity is challenging due to inclusion of vibration modes of molecules. In this report, photoluminescence excited by three different wavelengths is utilized. The alternation of fluorescence is observed, which may result from the variation of coupling strength during illumination. Furthermore, in addition to lower and upper polariton modes, the extra modes are observed. These results provide more insight into the molecule-cavity strong coupling

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The QKD with a DPS protocol at O-band is performed by employing a master-DFBLD to injection-lock a slave-DFBLD at almost identical wavelength. With the stabilization the master wavelength at 1308.4 nm for 10-min, the 1-bit delayed-interferometric decoding of the secure single-photon QKD codes with DPS states switched between 0 to pi is performed. By adding a small bias change under Ipp of 0.15mA or Vpp of 60 mV with corresponding wavelength of 0.6 pm (=phase change to pi) can be converted to on-off-keying format for QKD decryption with a QBER of 30% at a data rate of 1 Mbit/s.

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This research proposes a novel all-optical sub-THz signal generation based on period-one dynamics of two mutually coupled semiconductor lasers under highly asymmetric coupling strength. As a result, the generation of sub-THz signals ranging from 100 to 300 GHz with similar good phase quality, including a 3-dB linewidth below 2 kHz and a side-peak suppression ratio of about 46 dB, is achieved all-optically.

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The study focuses on stabilizing subharmonic nonlinear dynamics in semiconductor lasers for optical frequency comb (OFC) generation. The proposed system consists of two cascaded optical injection stages. By injecting the first stage with proper power and frequency, period-one (P1) dynamics are invoked, then leading P1 dynamic injection into the second stage. With adjusted power in the second stage, undamped relaxation oscillations trigger subharmonic nonlinear dynamics. This achieves OFC generation with subharmonic oscillation sidebands, generating over 15 comb lines, and a bandwidth greater than 140 GHz. We have also proposed a cascaded injection-locking scheme to improve microwave comb signal quality.

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In this work, we demonstrate a workflow to simulate VCSEL and SOA devices. The electronic part is calculated using a self-consistent MQW solver, the optical section of the device is solved using the FDTD method and the thermal model with a Joule heating solver. The connection between MQW and FDTD is achieved by implementing a current driven model in FDTD that allows for solving the rate equations using the fitted MQW data. Additionally, the heat distribution of the cavity can be used in the FDTD solver. With this workflow we can calculate the I-V and I-L curves of the VCSEL.

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The 2023 Nobel Prize in Physics was awarded jointly to Drs. Pierre Agostini, Ferenc Krausz, and Anne L’Huillier for their pioneering work in attosecond science. This talk will trace the history of attosecond science from its inception to the present day, highlighting key milestones and influential figures. We then delve into the contemporary applications of attosecond science, demonstrating how attosecond pulses have transformed the study of ultrafast processes. These applications encompass electron dynamics in atoms, molecules, and materials, enabling insights into chemical reactions and structural changes on timescales previously inaccessible. In addition, we highlight the notable contributions and developments in attosecond science within Taiwan, underscoring the global impact of this rapidly advancing field.

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Impulsive Stimulated Raman Scattering (ISRS) is a time-domain spectroscopic technique for studying molecular vibrations, which has superior sensitivity to traditional Raman spectroscopy. We achieve high-resolution observation of molecular vibration using the ultrashort pump and probe pulses. In our experiment, we kept the pump pulse duration fixed at 15 fs while varying its central wavelength. This approach confirms the enhancement of the Raman signal in the spectral region where the pump and probe overlap, consistent with the theoretical model and qualitative descriptions.

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In this study, we demonstrate bandgap engineering of InGaAs/GaAsSb multi-quantum well (MQW) structure grown on GaAs substrates for achieving emission wavelength above 1 μm. Three different structures were grown by molecular-beam epitaxy (MBE). Bandgap engineering simulations were carried out using COMSOL to identify the potential growth parameters for achieving wavelength of 1.3 μm.

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In this article, we demonstrate a self-stabilized all-fiber-based femtosecond laser light source for harmonic generation microscopy. By utilizing self-phase modulation in a photonic crystal fiber and feedback control, the 1220 nm femtosecond source accomplished week-long steady output power performance.

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We demonstrate a novel approach to energetic picosecond 10.2-µm pulse generation
based on nonlinear mixing of subnanosecond single-frequency 1338-nm pulses and broadband
1540-nm chirped pulses in a BGGSe crystal followed by a grating compressor for seeding high-
power CO2 amplifiers. 10.2-µm pulses with an energy exceeding 30-µJ, and their fluctuation is
∼3%-rms are produced routinely. On the basis of the measured pulse spectrum and a single-shot
pulse duration measurement, performed by Kerr polarization rotation time-resolved by a streak
camera, we conclude the measured pulse width is between 2.2-3 ps.

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We demonstrate a high-efficiency 1.55-μm buried heterostructure distributed feedback (BH-DFB) laser. Optimization of the LD structure demonstrated a threshold current of 12 mA and a differential slope efficiency of 0.433 W/A. Under high current and wide temperature conditions, its single-mode optical spectrum remains intact. From a single active region, the laser produces 6.27 W of optical power, which can be verified by pulsed signals. With attributes of high efficiency, singular modal spectra, eye-safety wavelengths, and watt-level optical power, this laser is a promising option for LiDAR systems.

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Cesium lead halide perovskite quantum dots (PQDs) in the all-inorganic form, CsPbX3 (where X = Cl, Br, I), exhibit remarkable optical characteristics suitable for diverse optoelectronic applications. Whispering-gallery-mode (WGM) resonators demand high symmetry, minimal loss, and a high-quality factor (Q). This research capitalizes on the strengths of both PQDs and WGM resonators by uniformly applying PQDs onto SiO2 microspheres. We studied resonant behavior across differently sized WGM cavities and explored resonance characteristics under varying polarizations in-depth. The simulations confirm the consistency of experimental WGM modes.

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Dissipative soliton resonance in a unique mode-locking regime, which allows
generating rectangular-shaped pulses with high energies directly from the laser resonator. We
present the first demonstration of achieving stable multipulsing in a dissipative soliton
resonance laser utilizing a double-clad ytterbium-doped active fiber. By carefully tailoring the
resonator parameters we were able to control the number of pulses generated in a single burst
by simply adjusting the pump power. Parameters and the stability of the generated pulses will
be presented and discussed.

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This study investigates the impact of metal contact misalignment in Vertical-Cavity Surface-Emitting Laser (VCSEL) fabrication on device optoelectronic properties, focusing on mode hopping. Experimental results reveal that imprecise alignment during photolithography causes significant fluctuations in light-current-voltage (L-I-V) behavior, particularly severe kinks in the light output power to drive current (L-I) curve. This phenomenon from laser light path obstruction, where misaligned annular metal contact blocks the output laser beam, leading to optical field distribution changes. The research findings emphasize the critical role of precision in VCSEL fabrication for stable mode characteristics.

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In this study, we purpose novel 3D display technology. We used a self-scattered mechanism of laser-induced plasma to create a monochromatic point cloud in the air. By analyzing the angular distribution and color of the scattered light, try to find the best condition for human eyes. This method can create 3D images without any other medium, and achieve true colorful 3D display.

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We report the observation of dynamical transition of multi-periodic laser pulses emitted from an intracavity second harmonic pulsed laser resonator which is built with Nd:YVO4 laser crystal and KTP nonlinear crystal via type-II phase matching scheme. Green laser pulses oscillate periodically and transformed among different types oscillatory patterns possibly due to the interplay between the saturable absorption and nonlinear frequency conversion.

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The ultrafast laser direct writing depressed waveguide in MgO:LN crystal was demonstrated. The depressed waveguide was based on a three-ring structure with diameters of 30 to 50 um, and processed by the pulse energy of 0.45 uJ, pulse repetition rate of 30.23 kHz, as well as annealed temperature of 150 degree. The measured propagation loss of no polarization was reached 0.73 dB/cm.

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This paper presents a high-brightness and high-power laser source, which is based on wavelength beam combining technology using full-bar diode laser stacks. The designed WBC system is demonstrated with 213 W output power and a central wavelength of 975 nm. The combined beam has BPPs of 5.01 mm-mrad on the slow axis and 5.74 mm-mrad on the fast axis. The smile effect of the diode laser and the thermo-optical effect are found to affect the beam quality of the combined beams. The results are helpful for systematically analyzing the wavelength beam combining system under a full-bar diode laser stack scheme.

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: The growth of silver nanoflowers using silver nitrate (AgNO3) and ascorbic acid as reducing agent is studied in this report. The silver nanoflowers caused by photo-reduction are allowed to grow on thin gold film of around 100 nm thickness. Here, pulsed femtosecond laser is used for the generation of hot electrons from the gold film to induce the formation of silver nanoflowers. The EDX analysis of the specimen confirms the presence of both silver and gold. This is to say that these nanoflowers are bimetallic nanostructures.

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This study utilizes a specific period PQ/PMMA VBG as an external resonant cavity for a semiconductor laser to achieve single longitudinal mode operation. Additionally, by modulating the voltage to control the liquid crystal, we introduce it into the external resonator cavity, creating a frequency-modulated continuous-wave laser source.

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In this paper, the nonlinear dynamics of the pulsed injected semiconductor lasers are studied. Optical frequency combs are generated by the period-one states in the optical spectra of the pulsed injected semiconductor lasers. The detailed characteristics of the optical combs under different operational parameters are also discussed.

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In this report, we investigate the nature of Amplified spontaneous emission in a maturely studied perovskite material. By studying the carrier dynamics and resolving the relaxation processes, we provide a more complete model which contribute to a deeper understanding of the underlying mechanisms and provide insights for optimizing the design and fabrication of perovskite-based lasers.

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Two-photon excitation microscopy for live biological samples requires a fast scanning speed, necessitating a high repetition rate light source. In this study, we successfully double the repetition rate of 2-W, 940-nm pulses from 2 MHz to 4 MHz using a multipass cell. The repetition-rate-doubled pulses still maintain a great beam profile, and the spectrum remains unchanged.

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We investigated the bendable band-edge laser from dye-doped cholesteric liquid crystal film (DD-CLCP film) by incorporation of chiral molecules (ISO-(6OBA)2) with nematic diacrylate monomer (RM257) and glued onto the PET substrates. Through mechanical stress, the band-edge lasing was generated under bending conditions and showing slight red-shift owing to the increase the pitch of helical structure.

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High harmonic generation is driven by short-wavelength electromagnetic waves in laser-plasma interactions. Its conversion efficiency is determined by the relative phase between the driving laser field and the harmonic field, which is affected by various dispersive effects. Therefore, we mainly proposed to achieve the dispersion balance between intrinsic dipole phase variation, Geometrical phase shift, and plasma dispersion under strong ionization regime. The scheme will be verified by numerical simulation for the HHG order 169th by 405-nm laser corresponding to the water window X-ray, i.e. 2.39-nm.

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We report on terahertz emission from topological material EuCd2As2 single crystals under ultrafast optical excitation with different polarization. Nonzero circular dichroism of the emitted THz radiation were observed as the polarization of optical pulses switch from right circular polarization to left circular polarization. The observed phenomena are coincident with circular photogalvanic effect. Our work demonstrates the potential applications of EuCd2As2 on opto-spintronics devices.

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This study demonstrate the CW(continuous wave) driven high power laser package which is with O-band and can used as CPO (co-package)’s light source. The laser diode is between the bottom submount and the upper submount for novel double-heat-flow to improve heat dissipation of the package. A stud bump is electrically connected to the second electrode of up submount and p-pad of DFB chip, heat dissipation, prevent the ridge damage.

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The DFB laser has been demonstrated by injecting an organic dye (PM597) solution into an empty polydimethylsiloxane (PDMS) microcavity structure. As pump energy increases above 6.3 J/cm2, the single lasing peak around 577 nm was excited with narrow linewidth around 0.949 nm. Under the different excited location on the cell, the wavelength tuning from 568.5 nm to 579.4 nm, with a total tuning range of 10.9 nm has been demonstrated.

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In this study, we use quantum transport modeling to explore the impact of gate-induced superlattices on graphene's band structure. At low magnetic fields, we examine carrier dynamics and simulate transverse magnetic focusing, revealing strong agreement with miniband structures from the continuum model. At high magnetic fields, our four-probe resistance matches the Hofstadter butterfly spectrum. Our modeling provides insights into miniband structures, applicable to various superlattice geometries.

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Mode locking is absent and irregular pulsation phenomena are observed in a coherent optical feedback 803 nm semiconductor laser using a semiconductor saturable absorber mirror with 3% modulation depth in a 50 cm cavity. The average time interval between pulses is 267 ns under 26 mA driving current which is slightly above threshold current. It drops to 31 ns when driving current is increased to 37 mA, right before irregular pulsing can be distinguished. The pulse width, ranged from 1.25 to 3.9 ns, depends on the driving current in the range of 26 to 37 mA.

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